(1) Field of the Invention
The present invention generally relates to the field of semiconductor devices. More specifically, the present invention relates to fabrication of semiconductor devices, particularly field effect transistors.
(2) Description of the Related Art
Silicon-on-insulator (SOI) technology is well-known in the art. This technology utilizes a layer of semiconductor material overlying an insulation layer formed on a supporting bulk wafer. An SOI structure may be formed by way of a number of well-known processes, such as separation by implanted oxygen (SIMOX), zone melting and recrystallization (AMR), or Bonded and Etchback (BESOI).
Typically, an SOI structure includes a silicon film formed on a layer of silicon oxide buried in a silicon substrate.
Field effect transistors, such as MOSFETs fabricated in the silicon film of an SOI structure, have many advantages over MOSFETs fabricated on traditional bulk silicon substrates. Such advantages include reduced parasitic capacitance, resistance to short-channel effect, steeper subthreshold slopes, increased current drive, higher packing density, and simpler processing steps. In the past, SOI applications have been limited due to high cost and inferior crystalline quality of SOI wafers. Nevertheless, recent advancements in the SOI silicon film quality, buried oxide quality, and manufacturing throughput have lead to numerous ultra large scale integration (ULSI) applications. The lower complexity/cost of SOI integrated circuit processes, relative to the constantly increasing cost of bulk silicon submicron integrated circuit processes, confers SOI technology a great potential becoming a preferred low cost mainstream production technology.